An optical waveguide mixes and directs light emitted by one or more light sources, such as one or more light emitting diodes (LEDs). A typical optical waveguide includes three main components: one or more coupling elements, one or more distribution elements, and one or more extraction elements. The coupling elements(s) direct light into the distribution element(s) and condition the light to interact with the subsequent components. The one or more distribution elements control how light flows through the waveguide and is dependent on the waveguide geometry and material. The extraction element(s) determine how light is emitted by controlling where and in what direction the light exits the waveguide.
After light has been coupled into the waveguide, it is guided and conditioned to the locations of extraction. In accordance with well-known principles of total internal reflectance the light rays continue to travel through the waveguide until such rays strike a light extraction surface and the light rays escape the waveguide. By appropriately shaping the waveguide surfaces, the position from which light is emitted and the angular distribution of the emitted light may be controlled. The design of the coupling elements, the distribution elements and the extraction devices provide control over the appearance of the waveguide, its resulting distribution of emitted light, and system optical efficiency.